1. Field of the Invention
The present invention relates to a method of charging coal into a coke oven in a manner to decrease the disparity in the degree of bulk density of coal charged into a coke oven in the vertical direction so as to obtain a resultant coke of stable quality. The invention also relates to an apparatus employed in the same method.
2. Description of the Related Art
In general, a regenerator is placed at the bottom portion of a chamber furnace-type coke oven in which the coke is produced. A plurality of carbonization chambers and combustion chambers are alternately disposed at the top portion of the coke oven. Coal is charged into the carbonization chambers through a plurality of charging inlets which are placed in the longitudinal direction of the respective carbonization chambers. Further explanation of the prior art method will be discussed later with reference to the drawings.
A disparity in the degree of bulk density of coal from the lower portion to the upper portion of the coke oven gives rise to inconsistencies in the strength of the resultant coke, thus resulting in low product quality and low productivity.
In order to solve these problems, various methods and apparatuses have been developed.
For example, the following method is disclosed in Japanese Patent Laid-Open No. 57-36183 and is aimed to decrease the inconsistencies in the strength of the resultant coke caused by a lower bulk density in the upper layer of the coal which has been charged into the carbonization chamber. A vibrator is disposed at the forward end of a coal leveller so as to pressurize and vibrate the upper layer of the charged coal the surface of which has been levelled, thereby further increasing the bulk density.
Japanese Patent Laid-Open No. 60-15487 discloses another method employed whereby a rotatable compacting roller is disposed at the forward end of a coal leveller so that it can press the upper layer so as to make it even.
Also, Japanese Utility Model Laid-Open No. 57-150538 discloses an apparatus having a coal hopper which is constructed to be vertically movable by a hydraulic cylinder so as to increase the distance travelled by coal during free fall and to charge it into a carbonization chamber.
Further, Japanese Patent Publication No. 60-23140 discloses the following method to achieve a uniform distribution in bulk density of coal charged into a carbonization chamber of a coke oven in the vertical direction. A loading apparatus using a pair of belts is employed to accelerate the coal at a suitable velocity so as to charge it into the carbonization chamber, thereby also controlling the packing density and the distribution of bulk density of coal within the carbonization chamber.
A further method is disclosed in Japanese Patent Laid-Open No. 58-142972 to feed coal into a casing located on a charging inlet so as to accelerate the coal with an impeller and to charge it into the carbonization chamber. This method employs the following technique in order to achieve uniform bulk density of the coal charged in the carbonization chamber. It is expected that the speed of coal particles will be reduced because of air resistance while being accelerated, and thus, in the first half of the charging, charging velocity of the coal is progressively accelerated, and in the second half, the degree of acceleration is decreased.
Japanese Patent Laid-Open No. 3-796 discloses a method to control the bulk density of a raw material (coal) to be charged and to control the distribution of the bulk density. When the coal is charged into a carbonization chamber through a charging inlet of a chamber furnace-type coke oven, a leveller having rotation vanes provided for an extruder is inserted into the carbonization chamber from a levelling inlet so that the coal which falls straight down through the charging inlet strikes the rotation vanes driven by a motor so as to be accelerated and to be dropped into the carbonization chamber.
All of the foregoing conventional methods and apparatuses encounter problems.
The methods disclosed in Japanese Patent Laid-Open Nos. 57-36183 and 60-15487 are respectively employed whereby the vibrator and the compacting roller, together with a leveller, are allowed to advance the carbonization chamber of the coke oven. However, the apparatuses employed in these methods are complicated in construction and function. They are likely to suffer from the generation of dust, and breakdown is likely to occur in the carbonization chamber in an atmosphere having a high temperature. Thus, such apparatuses are not suitable for use over a long period.
The method disclosed in Japanese Utility Model Laid-Open No. 57-150538 also presents problems. The vertically-movable coal hopper is complicated in construction and function. It is likely to suffer from the generation of dust, and a breakdown is also likely to occur in the carbonization chamber in an atmosphere having a high temperature. Thus, such a apparatus is not suitable for use over a long period. Further, the load placed in the apparatus becomes too heavy so as to increase the normal load with respect to the surface of the coke oven, resulting in an unfavorable increase in load on the oven.
Moreover, the methods disclosed in Japanese Patent Publication No. 60-23140 and Japanese Patent Laid-Open No. 58-142972 each encounters problems in that a large apparatus and a complicated control are required, which further necessitates intensive and careful maintenance of equipment.
Also, even without carrying out the method disclosed in Japanese Patent Laid-Open No. 58-142972, it is still possible to obtain a result that when the coal is charged only by free fall, the longer distance travelled by the coal, the higher velocity at which the coal falls.
Further, the method disclosed in Japanese Patent Laid-Open No. 3-796 encounters the following problems. Since the rotation vanes are located immediately under the charging inlet, the coal which has fallen through the inlet from the hopper does not strike the same position of the vanes, and thus, the coal which has temporarily struck the vanes scatters around the vanes. This makes it difficult to control the direction and the velocity in which the coal is dropped into the carbonization chamber.
No matter what method and apparatus described above is employed, it requires not only a large apparatus and complicated control, but also necessitates intensive and careful maintenance of equipment.